We will improve ultrasound (US) medical imaging technology by integrating a simultaneous noninvasive audible frequency measurement of biological sounds indicative of pathology. This multimode sonic / US imaging technique will advance diagnostic capabilities beyond the state-of-the-art and will be ideal for retrofit on existing systems. Measurement of naturally-occurring biological acoustic phenomena can augment conventional imaging technology by providing unique information about material structure and system function. Sonic phenomena of diagnostic value are associated with a wide range of biological functions, such as breath sounds, bowel sounds and vascular bruits. The potential range of applications can be further expanded by coupling the multimode technology with vibroacoustography, where one noninvasively insonifies a localized region of tissue via focused modulated US. The initial focus of the technology and of this proposal would be to provide an improved diagnostic tool for common peripheral vascular complications associated with arteriovenous (AV) grafts. The specific aim of this R21 application is to develop and evaluate the capability of the proposed sonic / US diagnostic technology to track and predict AV graft failure. To achieve this, we will: 1) construct the multimode system by combining a commercial US system with a novel sonic sensor array and associated instrumentation, 2) calibrate and improve its capability by conducting controlled phantom studies using simple and anatomically accurate geometries based on 3 dimensional in vivo US images, and 3) conduct serial feasibility studies on 3 human AV graft patients. An audible frequency (sonic) sensor array pad will be applied to the skin (or phantom) over which the peripheral vascular US probe is maneuvered. The US probe images the discrete sensors in the array in addition to the underlying anatomical structure. The array sensors detect and focus on diagnostically indicative sonic phenomena resulting from turbulent blood flow and its dynamic interaction with the vascular wall/graft and surrounding biological tissues. The sonic array provides unique diagnostic information unobtainable via US imaging. In addition to providing anatomical geometry the US image enables one to improve the focusing capability and consequently, diagnostic value, of the sonic array. The assembled research team for this project has the unique and necessary expertise in sonic wave motion in biological tissue, hemodynamic flow through vascular constrictions, and the relationship between vascular pathology and vibro-acoustic "signatures". Finally, it is emphasized that, while the initial focus here is on prediction of AV graft failure, the proposed diagnostic advancement has much wider eventual application to diagnosis and monitoring of numerous pathologies.